Abstract:
:A novel nonparametric regression model is developed for evaluating the covariate-specific accuracy of a continuous biological marker. Accurately screening diseased from nondiseased individuals and correctly diagnosing disease stage are critically important to health care on several fronts, including guiding recommendations about combinations of treatments and their intensities. The accuracy of a continuous medical test or biomarker varies by the cutoff threshold (c) used to infer disease status. Accuracy can be measured by the probability of testing positive for diseased individuals (the true positive probability or sensitivity, Se(c), of the test), and the true negative probability (specificity, Sp(c)) of the test. A commonly used summary measure of test accuracy is the Youden index, YI=max{Se(c)+Sp(c)-1:c∈ℝ}, which is popular due in part to its ease of interpretation and relevance to population health research. In addition, clinical practitioners benefit from having an estimate of the optimal cutoff that maximizes sensitivity plus specificity available as a byproduct of estimating YI. We develop a highly flexible nonparametric model to estimate YI and its associated optimal cutoff that can respond to unanticipated skewness, multimodality, and other complexities because data distributions are modeled using dependent Dirichlet process mixtures. Important theoretical results on the support properties of the model are detailed. Inferences are available for the covariate-specific Youden index and its corresponding optimal cutoff threshold. The value of our nonparametric regression model is illustrated using multiple simulation studies and data on the age-specific accuracy of glucose as a biomarker of diabetes.
journal_name
Biometricsjournal_title
Biometricsauthors
Inácio de Carvalho V,de Carvalho M,Branscum AJdoi
10.1111/biom.12686subject
Has Abstractpub_date
2017-12-01 00:00:00pages
1279-1288issue
4eissn
0006-341Xissn
1541-0420journal_volume
73pub_type
杂志文章相关文献
BIOMETRICS文献大全abstract::Spatial replication is a common theme in count surveys of animals. Such surveys often generate sparse count data from which it is difficult to estimate population size while formally accounting for detection probability. In this article, I describe a class of models (N-mixture models) which allow for estimation of pop...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/j.0006-341X.2004.00142.x
更新日期:2004-03-01 00:00:00
abstract::I discuss diagnostic methods for discriminant analysis. The equivalence with linear regression is noted and regression diagnostics are considered. The leverage is a function of the linear discriminant function and the Mahalanobis distance of the observation from the group mean. The distribution of this distance is app...
journal_title:Biometrics
pub_type: 杂志文章
doi:
更新日期:1997-12-01 00:00:00
abstract::Highly active antiretroviral therapy (HAART) has proved efficient in increasing CD4 counts in many randomized clinical trials. Because randomized trials have some limitations (e.g., short duration, highly selected subjects), it is interesting to assess the effect of treatments using observational studies. This is chal...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/biom.12564
更新日期:2017-03-01 00:00:00
abstract::Computer simulation has been used to compare four methods for calculating confidence intervals for simple rate ratios estimated from cohort studies. The method proposed by Cornfield (1956. In Proceedings of the Third Berkeley Symposium on Mathematical Statistics and Probability. Vol. IV, 135-148) for interval estimati...
journal_title:Biometrics
pub_type: 杂志文章
doi:
更新日期:1983-06-01 00:00:00
abstract::Alterations in DNA methylation have been linked to the development and progression of many diseases. The bisulfite sequencing technique presents methylation profiles at base resolution. Count data on methylated and unmethylated reads provide information on the methylation level at each CpG site. As more bisulfite sequ...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/biom.13000
更新日期:2019-06-01 00:00:00
abstract::Epidemiological studies of related individuals are often complicated by the fact that follow-up on the event type of interest is incomplete due to the occurrence of other events. We suggest a class of frailty models with cause-specific hazards for correlated competing events in related individuals. The frailties are b...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/biom.12326
更新日期:2015-09-01 00:00:00
abstract::A procedure is given for estimating the ratio of the means of two populations using the data from two independent random samples when the observations are normally distributed with population variances that are related to the population means. ...
journal_title:Biometrics
pub_type: 杂志文章
doi:
更新日期:1985-03-01 00:00:00
abstract::This paper studies randomization model methods for analyzing data from a multicenter study comparing the effectiveness of two treatments. The Mantel-Haenszel mean score statistic, which can be used for continuous or ordered categorical response variables, is shown to be a useful nonparametric alternative to standard l...
journal_title:Biometrics
pub_type: 杂志文章
doi:
更新日期:1995-09-01 00:00:00
abstract::A common measure in clinical trials and epidemiologic studies is the number of events such as seizures, hospitalizations, or bouts of disease. Frequently, a binary measure of severity for each event is available but is not incorporated in the analysis. This paper proposes methodology for jointly modeling the number of...
journal_title:Biometrics
pub_type: 杂志文章
doi:
更新日期:1997-09-01 00:00:00
abstract::In an effort to determine whether a particular treatment causes a particular outcome event, data are obtained from a database system that records events when they occur, and for such events, the system records exposure to the treatment. That is, the system records information about cases. The system provides no inform...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/j.0006-341X.2005.030920.x
更新日期:2005-03-01 00:00:00
abstract::A log-linear model for estimating the size of a closed population is defined for inverse multiple-recapture sampling with dependent samples. Efficient estimators of the log-linear model parameters and the population size are obtained by the method of minimum chi-square. A chi-square test of the general linear hypothes...
journal_title:Biometrics
pub_type: 杂志文章
doi:
更新日期:1987-12-01 00:00:00
abstract::In recent years, increasing attention has been devoted to the problem of the stability of multivariable regression models, understood as the resistance of the model to small changes in the data on which it has been fitted. Resampling techniques, mainly based on the bootstrap, have been developed to address this issue....
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/biom.12381
更新日期:2016-03-01 00:00:00
abstract::Interference occurs between individuals when the treatment (or exposure) of one individual affects the outcome of another individual. Previous work on causal inference methods in the presence of interference has focused on the setting where it is a priori assumed that there is "partial interference," in the sense that...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/biom.13125
更新日期:2020-03-01 00:00:00
abstract::We consider a capture-recapture model in which capture probabilities vary with time and with behavioral response. Two inference procedures are developed under the assumption that recapture probabilities bear a constant relationship to initial capture probabilities. These two procedures are the maximum likelihood metho...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/j.0006-341x.2000.00427.x
更新日期:2000-06-01 00:00:00
abstract::The variogram is a standard tool in the analysis of spatial data, and its shape provides useful information on the form of spatial correlation that may be present. However, it is also useful to be able to assess the evidence for the presence of any spatial correlation. A method of doing this, based on an assessment of...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/j.0006-341x.2001.00211.x
更新日期:2001-03-01 00:00:00
abstract::We study publication bias in meta-analysis by supposing there is a population (y, sigma) of studies which give treatment effect estimates y approximately N(theta, sigma(2)). A selection function describes the probability that each study is selected for review. The overall estimate of theta depends on the studies selec...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/j.1541-0420.2006.00705.x
更新日期:2007-06-01 00:00:00
abstract::In diagnostic medicine, estimating the diagnostic accuracy of a group of raters or medical tests relative to the gold standard is often the primary goal. When a gold standard is absent, latent class models where the unknown gold standard test is treated as a latent variable are often used. However, these models have b...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/j.1541-0420.2012.01789.x
更新日期:2012-12-01 00:00:00
abstract::To evaluate diagnostic tests, one would ideally like to verify, for example, with a biopsy, the disease state of all subjects in a study. Often, however, no all subjects are verified. Previous methods for evaluation assume that the decision to verify depends only on recorded variables. Sometimes, particularly if the d...
journal_title:Biometrics
pub_type: 杂志文章
doi:
更新日期:1995-03-01 00:00:00
abstract::Many techniques of functional data analysis require choosing a measure of distance between functions, with the most common choice being L2 distance. In this article we show that using a weighted L2 distance, with a judiciously chosen weight function, can improve the performance of various statistical methods for funct...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/biom.12161
更新日期:2014-09-01 00:00:00
abstract::Estimating the number of clusters in a data set is a crucial step in cluster analysis. In this article, motivated by the gap method (Tibshirani, Walther, and Hastie, 2001, Journal of the Royal Statistical Society B63, 411-423), we propose the weighted gap and the difference of difference-weighted (DD-weighted) gap met...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/j.1541-0420.2007.00784.x
更新日期:2007-12-01 00:00:00
abstract::The feasibility and cost-effectiveness of estimation of kappa using a case-control method of sampling, proposed by Jannarone, Macera, and Garrison (1987, Biometrics 43, 433-437), is provided support. However, in this article unrealistic assumptions in their presentation are identified and more general results for more...
journal_title:Biometrics
pub_type: 杂志文章
doi:
更新日期:1990-03-01 00:00:00
abstract::Conventional statistical determinations of sample size in phase II studies typically lead to sample sizes of the order of 25 (Schoenfeld, 1980, International Journal of Radiation Oncology, Biology and Physics 6, 371-374). When the development of new treatments is proceeding rapidly relative to the recruitment of suita...
journal_title:Biometrics
pub_type: 杂志文章
doi:
更新日期:1985-06-01 00:00:00
abstract::Heart rate oscillates in synchrony with respiration. Several methods have been employed to assess this 'sinus arrhythmia', as an index of autonomic nervous system function. This paper proposes a new, easily computed measure, R, which is relatively resistant to the major nonrespiratory sources of variation, including p...
journal_title:Biometrics
pub_type: 杂志文章
doi:
更新日期:1984-09-01 00:00:00
abstract::At any age the mean residual life function gives the expected remaining life at that age. Reliabilists and biometricians have found it useful to categorize failure distributions by the monotonicity properties of the mean residual life function. Hollander and Proschan (1975, Biometrika 62, 585-593) have derived tests o...
journal_title:Biometrics
pub_type: 杂志文章
doi:
更新日期:1983-03-01 00:00:00
abstract::The standard approach to inference for random effects meta-analysis relies on approximating the null distribution of a test statistic by a standard normal distribution. This approximation is asymptotic on k, the number of studies, and can be substantially in error in medical meta-analyses, which often have only a few ...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/j.0006-341x.1999.00732.x
更新日期:1999-09-01 00:00:00
abstract::Because the number of patients waiting for organ transplants exceeds the number of organs available, a better understanding of how transplantation affects the distribution of residual lifetime is needed to improve organ allocation. However, there has been little work to assess the survival benefit of transplantation f...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/biom.12084
更新日期:2013-12-01 00:00:00
abstract::Statistical methods for the detection of genes influencing quantitative traits with the aid of genetic markers are well developed for normally distributed, fully observed phenotypes. Many experiments are concerned with failure-time phenotypes, which have skewed distributions and which are usually subject to censoring ...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/j.1541-0420.2005.00346.x
更新日期:2005-09-01 00:00:00
abstract::When testing the null hypothesis that treatment arm-specific survival-time distributions are equal, the log-rank test is asymptotically valid when the distribution of time to censoring is conditionally independent of randomized treatment group given survival time. We introduce a test of the null hypothesis for use whe...
journal_title:Biometrics
pub_type: 杂志文章
doi:10.1111/1541-0420.00059
更新日期:2003-09-01 00:00:00
abstract::Procedures for estimating the genetic parameters of plant populations frequently employ progeny testing to ascertain the genotype of maternal plants. However, when experimental resources are limited (e.g., electrophoretic markers), the large progeny sizes required for accurate typing severely restricts the numbers of ...
journal_title:Biometrics
pub_type: 杂志文章
doi:
更新日期:1975-03-01 00:00:00
abstract::It is not, in general, possible to include all relevant risk factors in a model of survival or disease incidence. This heterogeneity must be accounted for in the interpretation, as it can imply otherwise unexpected results. This is illustrated by diabetic nephropathy, a serious complication experienced by some diabeti...
journal_title:Biometrics
pub_type: 杂志文章
doi:
更新日期:1994-12-01 00:00:00